Summary/Abstract Anabolic-androgenic steroids (AAS) use is a significant public health problem, with nearly 4 million Americans having used AAS. Roughly 30% of AAS users develop AAS dependence, among the highest dependence rates of all abused drugs. Polydrug abuse is highly prevalent among AAS users. AAS use causes acute psychiatric effects such as aggression and violence, and as we reported in past, long-term AAS use is associated with visuospatial memory dysfunction on tests predictive of early dementia. To date, human brain correlates of long-term AAS use are largely unexplored. Our pilot imaging studies in long-term AAS users produced 3 compelling findings. First, the amygdala is enlarged by AAS, consistent with controlled preclinical studies. Second, AAS reduced functional connectivity between the amygdala and dorsal anterior cingulate cortex (dACC), a cognitive control region. Third, in magnetic resonance spectroscopy studies, AAS users had elevated glutamine/glutamate ratios and lower scyllo-inositol levels in dACC, suggestive of ongoing dysfunction and possible neurotoxicity. As the amygdala participates in emotion regulation, visuospatial processing, sensory integration/processing of appetitive/aversive stimuli, cost/benefit decision-making, and drug reward, seeking, and cue reactivity, and together with the dACC modulates approach/avoidance learning and monitors emotional conflicts, amygdala and dACC abnormalities could impair all of these processes. Because commonly used AAS increase ?-amyloid levels and scyllo-inositol prevents ?-amyloid clumping, our scyllo- inositol finding may be particularly important. In this R01 application, we aim to build upon initial findings by directly probing amygdala and hippocampal function with task-based BOLD fMRI paradigms, including a source memory paradigm and the Hariri emotional face paradigm. We also will acquire MRS spectra from dACC and parieto-occipital cortex, the latter of which is a target for early ?-amyloid accumulation, to determine whether glutamine/glutamate and scyllo-inositol/creatine metabolite ratio abnormalities also occur in posterior cingulate cortex, a region normally exhibiting early ?-amyloid accumulation. Proposed studies involve large sample sizes that are adequately powered to test a priori hypotheses. Resulting data will help to identify the neural bases for psychiatric and cognitive abnormalities in AAS users, to gauge the severity of brain effects from long-term AAS use, and to inform the design of future studies to examine the progression of such effects with continued AAS use and/or aging, including interventional studies with agents such as scyllo-inositol or NMDA receptor antagonists. We have access to well-characterized AAS users and controls, recruited for our nearly-completed NIDA-funded cardiovascular studies, and the ability to recruit new subjects meeting inclusion/exclusion criteria. Our team is highly experienced with these populations and with proposed assessment methods, and thus is uniquely poised to conduct this research. Accordingly, this program is feasible and, if successful, likely will exert a sustained and powerful influence on the field.